U.S. patent number 5,294,178 [Application Number 07/795,765] was granted by the patent office on 1994-03-15 for tilt device for seat furniture.
This patent grant is currently assigned to Christof Stoll GmbH + CO KG. Invention is credited to Dagobert Bogle, Manfred Schlegel, Horst Ziegler.
United States Patent |
5,294,178 |
Bogle , et al. |
March 15, 1994 |
Tilt device for seat furniture
Abstract
In a tilt device for seat furniture, the base, which is fastened
to the chair bottom part and which carries a rotatable backrest
carrier for the backrest and a seat plate for the seat, is designed
as a closed carrier box composed of a plurality of sheet-metal
parts and is arranged between backrest cheeks of the backrest
carrier. A simple compact construction of the mechanism, which can
be used without appreciable changes for a permanent-contact
backrest and for a simultaneous mechanism, is obtained.
Inventors: |
Bogle; Dagobert (Laufenburg,
DE), Schlegel; Manfred (Kussaberg-Reckingen,
DE), Ziegler; Horst (Albbruck, DE) |
Assignee: |
Christof Stoll GmbH + CO KG
(Waldshut-Tiengen, DE)
|
Family
ID: |
8204836 |
Appl.
No.: |
07/795,765 |
Filed: |
November 21, 1991 |
Foreign Application Priority Data
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Dec 13, 1990 [DE] |
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90124041 |
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Current U.S.
Class: |
297/302.4;
297/365 |
Current CPC
Class: |
A47C
1/03255 (20130101); A47C 1/03238 (20130101) |
Current International
Class: |
A47C
1/022 (20060101); A47C 1/031 (20060101); A47C
1/026 (20060101); A47C 1/032 (20060101); A47C
3/02 (20060101); A47C 3/026 (20060101); A47C
001/032 () |
Field of
Search: |
;297/301,300,302,304,363-365 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0126839 |
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Dec 1984 |
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EP |
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0233974 |
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Sep 1987 |
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EP |
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2119641 |
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Nov 1983 |
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GB |
|
Primary Examiner: Brown; Peter R.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt
Claims
We claim:
1. A tilt device for seat furniture, comprising:
(a) a base which can be fastened to an underframe of the seat
furniture and which serves as a carrier for a seat and a
backrest;
(b) an angular backrest carrier with a lower leg and an upper leg,
said backrest carrier being rotatably mounted on the base in a
middle region of its lower leg by means of a rotary bearing and
consisting, at least in its lower leg, of two backrest cheeks
arranged parallel to and at a distance from one another;
(c) a seat plate which is supported at least in its front region by
the base; and
(d) at least one spring element having one end which is fastened to
the base and another end which engages the backrest carrier behind
the rotary bearing and exerts an upwardly directed force on the
backrest carrier;
wherein:
(e) the base is designed as a narrow closed carrier box which is
composed of a plurality of sheet-metal parts and which is arranged
between the backrest cheeks; and
(f) the carrier box has on its front side a sheet-metal crossmember
which projects laterally beyond the backrest cheeks and which
carries the seat plate in its front region;
the tilt device further comprising:
(g) a locking device having a locking pin which can engage into a
plurality of locking bores located at the front of the backrest
carrier, the locking bores being made directly on the front end of
one of the backrest cheeks, and the crossmember having on the side
which projects beyond the backrest cheek equipped with the locking
bores, two mutually spaced tabs which are perpendicular to the
crossmember and in which the locking pin is guided.
2. The tilt device as claimed in claim 1, wherein
(a) the sheet-metal parts of the carrier box and the crossmember
are deep-drawn sheet-metal parts or bent parts;
(b) the carrier box comprises a box-shaped lower part and a cover;
and
(c) the cover, the lower part and the crossmember are connected to
one another by means of a plurality of welding spots.
3. The tilt device as claimed in claim 1, wherein
(a) the tabs are designed as sheet-metal parts bent out from the
crossmember; and
(b) on one of the tabs there is a tolerance-compensating bearing,
in which the locking pin is guided with lateral play.
4. The tilt device as claimed in claim 1, further comprising means
for mounting the seat plate in its front region on the crossmember
in a horizontally displaceable manner.
5. The tilt device as claimed in claim 4, wherein
(a) the seat plate is rigidly connected in its rear region to the
carrier box; and
(b) the at least one spring element comprises a permanent
compensating spring having one end which is fastened on to the rear
end of the carrier box.
6. The tilt device as claimed in claim 5, wherein
(a) a rear region of the seat plate is rotatably mounted on the
backrest carrier; and
(b) the at least one spring element comprises a plurality of
simultaneous compensating springs which are arranged parallel to
the carrier box and which have one end fastened to the crossmember
and another end which engages on the backrest carrier via a
deflected pull cable.
7. The tilt device as claimed in one of claims 4-6, wherein, for
mounting the seat plate on the carrier box,
(a) ribbed seat bearings are provided in the rear region of the
seat plate;
(b) in the front region of the seat plate, part of the crossmember
is guided horizontally between supporting projections or a roller
running in ribs and counter-projections; and
(c) the ribbed seat bearings, supporting projections and
counter-projections are designed as parts formed on the seat
plate.
8. The tilt device as claimed in claim 1, wherein
(a) the rotary bearing for the backrest carrier comprises an axle
shaft which is pressed into the carrier box; and
(b) for fastening the carrier box to the underframe of the seat
furniture there is a receiving cone which is pressed into the
carrier box.
9. The tilt device as claimed in claim 1, wherein
(a) the locking pin of the locking device is cranked
perpendicularly to the pin axis at its end facing away from the
locking bores; and
(b) the cranked end is guided, by means of a stepped sleeve
attached resiliently onto it, in a recess which has the form of a
thread segment and which is designed as a slotted guide.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of seat furniture. It
relates particularly to a tilt device for seat furniture,
comprising
(a) a base which can be fastened to an underframe of the seat
furniture, preferably a chair column, and which serves as a carrier
for a seat and a backrest;
(b) an angular backrest carrier with a lower leg and an upper leg,
said backrest carrier being rotatably mounted on the base in the
middle region of its lower leg by means of a rotary bearing and
consisting, at least in its lower leg, of two backrest cheeks
arranged parallel to and at a distance from one another;
(c) a seat plate which is supported at least in its front region by
the base; and
(d) at least one spring element which is fastened to the base on
one side and which on the other side engages on the backrest
carrier behind the rotary bearing and exerts an upwardly directed
force on the backrest carrier.
Such a tilt device is known, for example, from EP-B1-0,233,974 of
the same applicant.
2. Discussion of the Related Art
Two solutions conducive to dynamic sitting have found
acceptance:
(1) As a basic version, chairs with a so-called "permanent-contact
backrest", that is to say with a backrest mechanism which generates
a specific countermoment, in order to compensate the variable
leaning moment of the chair user by means of the tilting range of
the backrest. The range of countermoments generated can at the same
time, if appropriate, be adjusted to the individual weight of the
user's upper body.
(2) As a sophisticated version, chairs or armchairs with a
so-called "simultaneous" or "synchronous" mechanism. In this
mechanism, the seat too--coupled with the permanent-contact
backrest--varies its tilt in a specific ratio. Especially when the
tilting ranges of the backrest are relatively wide, this
simultaneous or synchronous change of the seat tilt is a necessary
measure, in order, among other things, to counteract the forward
displacement of the buttocks which occurs as a result of the
leaning moment.
In the publication mentioned in the introduction, although a chair
mechanism allowing the two above-explained possibilities of
variation is described, nevertheless this known chair mechanism has
essentially the following disadvantage:
The basic elements of the mechanism (housing, springing, locking,
etc.) are designed for the complicated simultaneous mechanism. The
constructional outlay and production costs are therefore
considerable, because, in principle, a simultaneous mechanism has
to be "scaled down", in order to obtain a simpler permanent-contact
mechanism. At the same time, the relatively expensive housing made
of cast metal or fiber-reinforced plastic, the complicated
selectively usable locking for retained positions and other special
designs of the mechanism are preserved.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a chair mechanism
in the form of a tilt device, which is distinguished by a
simplified construction, can be produced cost-effectively in
relatively large series and, starting from the simpler
permanent-contact mechanism, can be extended by means of only a few
additional parts to form a simultaneous mechanism.
The object is achieved, in a tilt device of the type mentioned in
the introduction, in that
(e) the base is designed as a narrow closed carrier box which is
composed of a plurality of sheet-metal parts and which is arranged
between the backrest cheeks; and
(f) the carrier box has on its front side a sheet-metal crossmember
which projects laterally beyond the extended backrest cheeks and
which carries the seat plate in its front region.
The essence of the invention is to provide, as a receptacle for the
chair column and as a carrier for the seat and backrest, a closed
narrow carrier box which consists of few sheet-metal parts and is
located between the backrest cheeks and which in the front part
guarantees a support of the seat over a wide base by means of an
additional crossmember.
Such a carrier box can be produced simply and cost-effectively,
can, if required (for example, for the more complicated
simultaneous mechanism), easily be supplemented by additional parts
and as a result of the box design achieves a very high bending and
torsional resistance, while at the same time ensuring that only a
small amount of material is used.
According to a first preferred embodiment of the invention, the
crossmember serves at the same time as a supporting and guiding
bearing for the locking device of the permanent-contact or
simultaneous mechanism, in that
(a) there is a locking device, with a locking pin which can engage
into a plurality of locking bores made at the front of the backrest
carrier;
(b) the locking bores are made directly on the front end of one of
the backrest cheeks; and
(c) the crossmember possesses, on the side which projects beyond
the backrest cheek equipped with the locking bores, two mutually
spaced tabs which are perpendicular to the crossmember and in which
the locking pin is guided.
A further preferred embodiment of the invention is defined in
that
(a) the sheet-metal parts of the carrier box and the crossmember
are deep-drawn sheet-metal parts or bent parts;
(b) the carrier box comprises a box-shaped lower part and a cover;
and
(c) the cover, lower part and crossmember are connected to one
another by means of a plurality of welding spots.
Sheet steel is preferred in all cases as a material for the
sheet-metal parts.
Further embodiments emerge from the subclaims.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be explained in more detail below by means of
exemplary embodiments in conjunction with the drawing. In this:
FIG. 1 shows, in crosssection, a first exemplary embodiment of a
tilt device according to the invention in the form of a simplified
permanent-contact mechanism with a fixed seat plate;
FIG. 2a shows a second exemplary embodiment, similar to that of
FIG. 1, of a tilt device according to the invention in the form of
a simultaneous mechanism with a variable tilt of the seat
plate;
FIG. 2b shows in cutout form a front mounting, alternative to FIGS.
1 and 2a, of the seat plate on the crossmember;
FIG. 3 shows a top view of the simultaneous mechanism according to
FIG. 2a with details of the springing and locking;
FIG. 4a shows, in crosssection, a preferred exemplary embodiment of
a slotted guide of the locking pin of FIG. 3;
FIG. 4b shows a preferred guide path from the slotted guide
according to FIG. 4a in the form of a thread segment; and
FIGS. 5a and 5b show the individual carrier box with crossmember
according to FIGS. 1 to 3 in a side view (a) and top view (b).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first preferred exemplary embodiment of a chair mechanism
according to the invention is reproduced in FIG. 1 in the form of
the simpler permanent-contact mechanism.
The main part of this tilt device is an only partially visible
carrier box 4 which, as can be seen more clearly in FIGS. 5a and
5b, is composed of a box-shaped lower part 2, of a cover 1 arranged
on this and of a crossmember 3 attached to the front side (in
relation to the chair).
The lower part 2, cover 1 and crossmember 3 are preferably
deep-drawn or bent parts of sheet steel which are connected
integrally by spot welding to form the finished carrier box 4. At
the same time, as shown in FIG. 5a, the crossmember 3 can be a
special sheet-metal part which is welded to the lower part 2 and to
the cover 1, or else it can be formed together with the lower part
2 from a sheet bar by appropriate bending.
The carrier box 4 receives the (usually rotatable) chair bottom
part. This is carried out either in a way known per se by means of
a conical plug connection or directly by welding a chair column of
the chair bottom part (4a in FIG. 1) into the carrier box 4. Where
the conical plug connection is concerned, there is in the carrier
box 4 a receiving cone 2a which can be formed from the lower part 2
or, for example, is introduced nonpositively or positively as a
separate part (especially an extruded part) into the carrier box
4.
Bent on one side of the crossmember 3 are two tabs 5 and 6 which
have passage bores and which are part of a locking device explained
in more detail later in conjunction with FIGS. 3, 4a and 4b.
A seat plate 16 and a backrest carrier 18 are at the same time
fastened to the carrier box 4. The seat plate 16 is supported
(displaceably in principle) on the crossmember 3 in the front
region by means of supporting projections 22 and
counter-projections 24 and itself carries a seat cushion (not shown
in FIG. 1). It is firmly connected, if the permanent-contact
mechanism is used, to the carrier box 4 in the rear region by means
of a seat stay 34. The backrest carrier 18 is angular with an upper
and a lower leg. It is mounted rotatably on the carrier box 4 in
the middle region of its lower leg and on the upper leg carries a
backrest (likewise not shown).
Furthermore, the backrest carrier 18 is of asymmetric design, that
is to say it consists (at least in its lower leg) of two U-shaped
backrest cheeks 8 and 9 (FIG. 3) of unequal length and arranged
parallel to and at a distance from one another. The shorter
backrest cheek 9 terminates directly behind the rotary bearing. The
longer backrest cheek 8 is located on the side of the locking
device and is so shaped at its front end that locking bores 10 can
be made there.
The backrest carrier 18 is mounted rotatably on an axle shaft 19.
The axle shaft 19 is itself connected to the carrier box 4, that is
to say, for example, is pressed into corresponding bores. The two
backrest cheeks 8 and 9 are connected to one another in a
torsion-resistant manner behind the rear end of the carrier box 4,
preferably by means of a welded-in (round or angular) tubular piece
35a. Further cross connections, such as, for example, the tubular
piece 35b, are provided elsewhere, in order to form a limit stop
for the vertical adjusting range of the backrest and at the same
time make it possible to fasten cladding parts.
The necessary torsional resistance of the backrest carrier 18
loaded on one side is deliberately assisted by its narrow design,
in that the torsional moment introduced is kept low. One or more
permanent compensating springs 20, which are arranged between the
rotatably mounted backrest carrier 18 and the rear end of the
carrier box 4, compensate the leaning moment of the upper body when
it leans against the permanent-contact backrest of FIG. 1.
As already mentioned previously and as can easily be seen in FIGS.
3 and 5b, the two tabs 5 and 6 are bent on one side of the
crossmember 3 and have passage bores for guiding a locking pin 7.
Since, as a result of constructional tolerances, the locking pin 7
is never aligned exactly with the associated locking bores 10 in
the backrest cheek 8, the locking pin 7 is preferably guided in a
tolerance-compensating bearing 11 mounted so as to be displaceable
perpendicularly to the direction of movement of the pin (FIG. 3).
The tolerance-compensating bearing 11, which consists, for example,
of a resistant plastic, is snapped into an appropriately shaped
orifice in the tab 6. A suitably shaped tip on the locking pin 7,
in conjunction with the displaceable tolerance-compensating bearing
11, guarantees that the locking pin 7, even when off-center, is
automatically positioned centrally in one of the locking bores
10.
A locking spring 12 constantly presses the locking pin 7 into one
of the locking bores 10 under appropriate prestress. When the
locking pin is pulled outwards, the lock is released. The backrest
can then be used as a permanent-contact backrest. There is, at the
same time, a plurality of possibilities for keeping the locking pin
7 in the two different positions. The locking device can be
operated especially simply, cost-effectively and easily if the
locking pin 7 is cranked at the end and if the cranked end is
guided at a particular distance from the pin axis in a recess which
has the form of a thread segment 15a (FIG. 4b). The locking pin 7
is displaced in the direction of the pin axis by the pitch of the
thread segment 15a as soon as the cranked end runs rotationally up
against the thread segment 15a.
Thus, when the cranked end of the locking pin 7 is appropriately
moved by hand, the locking pin 7 is pulled out of the lock counter
to the increasing force of the locking spring 12. It conversely
locks automatically. The thread segment 15a acts as a reducing
transmission. Appropriately shaped recesses at the ends of the
thread segment 15a ensure that the locking pin, when released or
locked, remains in position.
To prevent the lock from being released unintentionally, the thread
segment 15a is preferably designed as a slotted guide 15b (FIG.
4a). A stepped sleeve 13 is pushed over the cranked end of the
locking pin 7. The stepped sleeve 13 has an edge which, by means of
an appropriately large diameter, in principle prevents the sleeve
from being pressed out of the slot by an internal spring 14,
specifically irrespective of the particular position in which the
pin end is located at that movement.
The diameter of the step under the edge fits into the larger slot
cutouts in the locking and release positions of the pin, but is too
large for the actual guide slot. Only when the stepped sleeve 13 is
pressed upwards counter to the force of the spring 14 can the pin
end move through the slot. The specific movements--first pressing
and then displacing--prevent the lock from being released
unintentionally if, for example, the user knocks against the pin
end.
Of course, the operating mode of this release safeguard can also be
reversed, by the stepped sleeve 13 being pulled downwards counter
to a tension spring which frees the slot.
With a view to a simple and cost-effective solution, the slotted
guide 15b is preferably the formed-on version of a seat cover 17
(FIGS. 1 and 4a). The seat cover 17 is in this case firmly
connected either to the seat or to the carrier box 4. In the
exemplary embodiment of FIG. 1, the connection to the seat plate 16
has been chosen. In particular, a larger space is available there,
and the technical preconditions for a simple snap or clip
connection are better on both parts, especially when they are
injection-molded from plastic.
For the version with the more complicated synchronous mechanism
(FIGS. 2 and 3), it is necessary to have the following forms of
construction which can partially be identical in terms of
construction to parts of the above-described permanent-contact
mechanism:
In this case, the seat plate 16 is rotatably mounted on the
backrest carrier 18 behind the axle shaft 19 by means of a further
axle shaft 31. The bores necessary for this and the
force-transmitting connection part are preferably obtained in an
especially simple way by means of formed-on ribbed seat bearings
21. This is possible when the seat plate 16 is a molding, that is
to say, for example, is injection-molded from plastic. If the axle
shaft 31 is secured axially in the longitudinal direction in the
customary way, for example by means of two retaining washers, the
rearwardly tiltable seat is fastened immovably in the longitudinal
and transverse directions. Moreover, as can be seen from FIG. 1,
the ribbed seat bearings 21 can also be present in the
permanent-contact mechanism, but in this case inoperative, for the
sake of simplified production.
The tilt ratio of the seat plate 16 or seat in relation to the
backrest is determined by the position of the rear and front
bearing points of the seat plate 16 in relation to the position of
the axle shaft 19. To keep the "leg-lifting effect" as low as
possible, the front bearing point of the seat plate 16 will be
located as near as possible to the front edge of the seat.
As already mentioned previously in the description of the
permanent-contact backrest, the seat plate 16 is supported in the
front region on the crossmember 3 on the right and left by means of
the formed-on supporting projections 22. The supporting projections
22, by virtue of their rounded shape, allow some unimpeded tilt
variation. Lateral displacement is preferably prevented by a
respective lateral retaining rib 23 which is formed externally on
the seat plate 16 on the left and right near the end of the
crossmember 3. Hooks which come from the seat plate 16 from above
and engage round the crossmember 3 on the right and left and which
have formed-on counter-projections 24 retain the seat plate 16 in
the upward direction. The hooks are preferably likewise formed on
the seat plate 16.
Thus, the seat plate 16 is retained on all sides, but remains
longitudinally displaceable, so that the relative travel occurring
at the rear fastening can be compensated. The mutually opposite
projections 22 and 24 guarantee that the tilt of the seat can vary
to a sufficient extent. As shown in FIG. 1, for the sake of
simplified production, this fastening system can likewise also be
used for the permanent-contact mechanism.
The described fastenings of the rear and front are an integral part
of a single seat plate 16 which can be used unchanged for both
mechanism versions. The seat cover 17 with the slotted guide 15b
and with the locking pin 7 guided in this can likewise be adopted
unchanged: although, the seat changes its tilt and position in
relation to the locking pin 7 mounted in the crossmember 3,
nevertheless the width distance between the backrest carrier 18 and
the cranked end of the locking pin 7 does not change. This fact
guarantees that the selected construction will function reliably.
The slight changes in position in the longitudinal direction which
occur during a tilting of the seat are insignificant in this
respect.
Higher-quality simultaneous compensating springs 25a, b are
provided (FIG. 3) as spring elements in the synchronous mechanism
instead of the simpler permanent compensating springs 20. These
inevitably afford a substantially higher working capacity than the
permanent compensating springs 20. In particular, they have to
compensate the leaning moment and the greatest part of the sitting
weight of the user. The simultaneous compensating springs 25a, b
can be accommodated in a space-saving and inconspicuous manner
approximately horizontally under the seat next to the mechanism and
next to the backrest carrier 18 in a way known per se. This
arrangement is advantageous, since, in this case, one of the two
ends of the springs can be fastened respectively to the crossmember
3.
The predominantly vertically effective change in travel of the
backrest carrier 18 is transmitted to the springs by means of pull
cables 27 which are deflected by deflecting rollers 28 or, to save
constructional height, deflecting segments 28a mounted on an angle
lever 26.
So that the synchronous mechanism can be adjusted to the user's
individual body weight, it is sufficient to make one of the two
simultaneous compensating springs (25b) variable in length and
therefore in spring force. This can be carried out, for example,
via a rotation-proof threaded rod 29 with a formed-on suspension
lug for the spring. A hollow rotary knob 30 with a thread, which is
supported on the crossmember and which receives in it the free end
of the threaded rod, makes the desired individual adjustment
possible.
In the simultaneous mechanism, where the previously described
longitudinally movable fastening of the seat at the front is
concerned, the friction between the supporting projection 22 and
the crossmember 3 located under it always has to be overcome. To
reduce these frictional forces, the supporting projections 22 can
advantageously also be replaced by a roller 33 which is snapped
into ribs 32 formed on the seat plate and which is mounted therein
(FIG. 2b). Another possibility provides coupling members (for
example, made of plastic) which are respectively fastened rotatably
to the seat plate 16 and to a bracket on the right and left.
* * * * *